Today, power converters are commonly used in conjunction with various devices such as light emitting diode (LED) assemblies, automobiles, mobile phones, tablets, computers, and other devices to convert line voltages, into various output voltages and currents. Often a power converter is configured to provide a constant output current, while the output voltage may fluctuate over time.
One type of power converter commonly used today is a switched mode power supply. Switched mode power supplies may include the use of various topologies, including buck converter, boost converter, inverting and flyback. The flyback topology commonly includes a transformer having a first (primary) coil that is electrically isolated from a second (secondary) coil, and often a third (sensing) coil. The primary coil is commonly coupled to an input power source and the secondary coil is commonly coupled to a load, such as an LED assembly. Typically, one of two approaches are used to regulate a power converter such that a constant current can be provided to a load. For a first approach, the output current is monitored at the secondary coil and the values thereof are relayed back to the primary side, where the regulating occurs by adjusting the frequency and/or pulse width during which the currents arise in the primary coil of the transformer. Such secondary side regulation often involves the use of opto-couplers or other components to provide electrical isolation between the primary and secondary sides of the power converter. Secondary side regulation, however, is a complex solution. For the second approach, primary side regulation is used, where the output current on the secondary side is approximated based upon the input voltages and currents sensed on the primary side of the power converter. It is commonly appreciated that by adjusting the duty cycle (the ratio of the time that the primary coil is “on” versus the total time the primary coil is both “on” and “off” time), the voltages induced in the primary coil and thereby in the output voltage of the transformer may be varied. Likewise, by adjusting the operating frequency, the currents produced by the power transformer may be regulated. While primary side regulation is common in low-power implementations, for medium and high-power implementations, for example, those where resonant circuit technologies are utilized, a suitable primary side regulation technique is needed.
The various embodiments of the present disclosure address the above and other concerns by providing devices, systems, and methods for providing primary side regulation in medium and high-power power converters, including those using resonant circuit technologies.